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It is of great practical significance to manufacture ceramic membranes with good reusability. We used a macromolecular gel network for in situ enhancement of a reticulated skeleton ceramic (RSC) membrane. The prepared RSC membranes were firstly characterized to determine their physical and chemical properties. The sample calcined at 1400 °C has a porosity of 41.66 %, a pore size of 0.34 μm, a mechanical strength of 4.53 MPa, and a permeability of 63.92 L m−1 h−1 bar−1. This membrane can effectively reduce the content of total organic carbon (TOC) (80 %) and calcium ion (>85 %). In addition, the flux of RSC fouled by alginate, calcium ions, or their mixture is effectively recovered by simple chemical rinsing using sodium hydroxide and ethylenediaminetetraacetic acid.

The effects of ethylene-vinyl acetate copolymer (EVA) and dicumyl peroxide (DCP) addition on injection moldability and tensile properties of recycled polyethylene (PE) from disposable drip tapes were studied. DCP showed an adverse impact on the injection moldability of recycled PE materials, while EVA had positive effects on it. Tensile properties of the reproduced PE increased with the increasing amount of EVA up to 10 wt.% and decreased beyond it. The DCP addition reduced the elastic properties of the reproduced PE, while it enhanced the tensile strength. Overall, the co-addition of 6 wt.% EVA + 0.4 wt.% DCP could improve the tensile strength of the reproduced PE materials.

In order to maintain sustainable agriculture, the flow in irrigation systems needs to be managed remotely and finely to achieve efficient use of water resources. This research develops a flow measuring device that integrates measurement and control to achieve precise flow regulation under remote control. The device chooses the angular regulating valve as the actuation component to control the flow. By the experimental study of the valve body working characteristics, this paper (1) establishes the relationships among the pressure in front of the valve, the valve body opening and the pipeline flow; (2) establishes the relationship between the valve opening degree and the number of driving pulses of the stepper motor, and (3) designs the opening decision and flow measurement software. The experiment shows that the flow coefficient of the valve body is 84.61, and there is no leakage loss when closed. It also shows that the regulation curve matches the law of fast-opening features. The established relationship and the correlation coefficient between the performance parameters and the measured value are both greater than 0.99, indicating a decent performance of fitness. In a test where the pipeline pressures were 0.10, 0.20, and 0.30 MPa, the average duration of flow regulation was 62.48 s, with a maximum overshoot of 5%, and a maximum steady-state error of 6%. The experiment also showed that the higher the pressure is, the better the regulation effect is. The flow measurement error under varied pressure is below 3%. With its simple structure, fast flow regulation time, and high accuracy, this device meets the requirements of flow management in irrigation systems. It can be used in a variety of flow rate remote monitoring and control scenarios.

Developing an ultra-thin polyamide selective layer with sufficient mechanical robustness on a highly porous ceramic substrate is challenging for removing heavy metal ions from wastewater. We synthesized a reliable ceramic-polyamide membrane by assembling nanocomposite interlayers of alumina and carbon black on the kaolin substrate. The surface morphology, pore size distribution, and roughness of ceramic substrates were improved by introducing the nanocomposite interlayer. The corresponding optimized water flux, Pb(II), and Cd(II) removal efficiency are 2.75 L m

Larger diameter and velocity and smaller landing angle of sprinkler irrigation droplets are more likely to cause soil splash and erosion. However, the mechanism of crop canopy influence on the physical parameters of sprinkler droplets is unknown. In this study, with the landing angle of sprinkler irrigation droplets as the independent variable and maize plants (Zea mays L.) as the research object, an indoor sprinkler irrigation experiment was carried out. The effects of maize canopy and variation in sprinkler irrigation droplets landing angle on the value and spatial distribution pattern of size, the velocity, and the landing angle of throughfall droplets was analyzed. In addition, the spatial variation patterns of throughfall droplets size, velocities’ distribution, and individual droplet’s speed, kinetic energy were also explored. The results showed that maize canopy and the decreasing of the sprinkler irrigation droplet landing angle had a positive and obvious effect on reducing the size and velocity of penetrating rain droplets. However, the throughfall droplets’ landing angles were only small variations. When the landing angle of sprinkler irrigation droplets was &gt, 45°, the spatial distribution of throughfall droplets size and velocity corresponded well with the canopy structure and leaf projection area of maize, i.e., the further away from the maize stalk, the larger the size and velocity of throughfall droplets. Nevertheless, if the landing angle of sprinkler irrigation droplets was &lt, 45°, the spatial distribution mentioned above was mainly affected by droplets landing angle. The spatial variation of throughfall droplets’ size and velocities at different measurement points was attributed to the change of the larger droplets’ volume proportion and the equivalent velocity. Although the maize leaves had a certain degree of perturbation effect on the velocities and kinetic energy of the larger kinetic energy droplets, the flight path of these drops did not alter significantly. The results of this research will be of practical value in guiding the development of a new sprayer and the optimum selection of sprinkler heads.

This study focuses on a fuzzy generalised predictive control (FGPC) method for a time-delay hydro-turbine governing system (HTGS). First, based on the time-delay Takagi-Sugeno fuzzy model, a time-delay HTGS and its fuzzy prediction model are given. Second, with the help of delay fuzzy linearisation and a fourth-order Runge-Kutta algorithm, a transformed controlled auto-regressive integrated moving average model is obtained. Then, a new FGPC scheme for the time-delay HTGS is proposed. Finally, numerical simulations are implemented to verify the validity and superiority of the proposed method. It also provides a reference for the stability control of relevant hydropower station systems.

In subsurface irrigation, emitter orifices can become clogged by root intrusion. Using the technologies of subsurface drip irrigation, porous ceramic moulding and 3D printing, a new ceramic patch type subsurface drip irrigation line (CP-SDIL) with a simple structure was developed. The CP-SDIL consists of a plastic pipe, a plastic patch, a porous ceramic water-seepage pad and a rubber leakage-proof gasket. The CP-SDIL discharge can be adjusted by changing the material of the ceramic water-seepage pad which is the core component. The CP-SDIL pressure–discharge relationship is linear, and the flow region index is one. The working pressure and the ceramic materials had a significant influence on the discharge of water from the CP-SDIL into the soil. The higher the ceramic porosity and the working pressure, the larger the discharge and the movement of the wetting front. Based on a theoretical analysis and using the reference value for the soil saturation zone radius, an equation for calculating the discharge from CP-SDIL into the soil was developed. The results of this study can be used as a reference for the promotion and application of CP-SDIL.

High energy consumption is one of the disadvantages of hose-drawn travelers due to the use of water turbines. This study proposes a photovoltaic-powered electric motor instead of a water turbine to achieve high transmission efficiency. A stand-alone photovoltaic generation system (PVGS) was designed for a hose-drawn traveler. To achieve cost savings, a sizing optimization model was built for the PVGS. In the optimization model, the minimum annual cost of the system, which includes the initial capital, replacement, installation, operation, and maintenance costs, is taken as the objective function. The constraints include the battery’s state of charge (SOC) and the power supply reliability, which is composed of the load loss of power supply probability (LPSP) and the energy excess percentage (EXC). The total power produced by the PV panels and the total battery capacity are the decision variables. The optimization model of the PVGS is solved through a particle swarm optimization (PSO) algorithm based on a penalty function. The model is then applied to calculate the optimal configuration of a JP75-300 hose-drawn traveler. Comparisons between the optimal configuration and other six configuration schemes were conducted to verify the optimal solution results. Furthermore, field experiments were performed to test the performance. Finally, the effects of meteorological conditions, driving velocity, and LPSP on the optimal configuration and the annual cost of the PVGS are discussed. The results show that the optimal configuration of this PVGS are 432 W total power from PV panels and 172 Ah total battery capacity, and the optimization model results are the optimal configuration based on comparisons. The optimal configuration met the power requirements of the hose-drawn traveler for four days of field experiments, indicating that the optimal configuration is feasible.HighlightsA photovoltaic-powered electric motor instead of a water turbine was used for high transmission efficiency.An optimization model was built to define the optimal configuration of the photovoltaic generation system (PVGS).The optimal configuration decreased the annual cost of the PVGS while ensuring power supply reliability.Meteorological conditions, driving velocity, and LPSP are key factors affecting the annual cost of the PVGS. Keywords: Driving power requirements, Field experiments, Hose-drawn traveler, Optimization model, Particle swarm optimization, Photovoltaic generation system.

It is of great significance to develop a new gravity-driven filter to remove water pollutants, but it is still challenging. Here, a novel and simple strategy is demonstrated to manufacture fly ash (FA) ceramic foams showing a three-dimensional interconnected porous structure, with multiwalled carbon nanotubes (MWCNTs) implanted by combining carbamate grafting and polydimethylsiloxane coating. The polydimethylsiloxane formed a physical coating on the carbamate group, generating an effective thermal insulating layer on the outer side of the entire MWCNT. The FA foam, which shows a sufficient adsorption capacity for Pb(II) (51.67 ± 1.17 mg g−1) and Cd(II) (30.12 ± 0.37 mg g−1) at pH = 5, T = 25 °C, has a 96.33%, 95.12%, 89.50% removal efficiency for Cd(II), Pb(II), and particulate pollutants, and exhibits excellent recycling performance. This paper provides new opportunities to fabricate gravity-driven filters with low energy consumption for wastewater treatment.

Low pressure oscillating water flow can reduce the investment and energy consumption of irrigation. It is also effective in reducing the clogging of an emitter and improving the spraying quality of sprinklers. In order to overcome the problem of the complex process in calculating the amplitude of the pressure head loss of oscillating water flow in different types of pipes, in this study, an empirical equation for the amplitude of the pressure head loss of oscillating water flow in different types of pipe has been developed. Further, validation experiments have been conducted to verify the accuracy of the calculated amplitudes of the pressure head loss by the empirical equation. The results show that average relative error between the measured and the calculated amplitudes of the pressure head loss by the empirical equation is 10.77%. Since the relative errors are small, it is an indication that the amplitudes of the pressure head loss calculated by the empirical equation are accurate. For the empirical equation developed in this study, the sensitivity of the model parameters has been analyzed. The results show that the amplitude of velocity, the internal pipe diameter, and the length of pipe are classified as highly sensitive. The average velocity, the period of oscillating water flow, and the modulus of elasticity of the pipe material are classified as sensitive. The thickness of the pipe wall is classified as medium sensitive. Compared with the calculation models of the existing researches, the empirical equation reduces the number of parameters required to be calculated, by which many complicated calculations are avoided, which greatly improves the computing efficiency. This is conducive to the efficient operation and management of oscillating water flow in irrigation pipe networks and also provides help for the optimal design of irrigation pipe networks.

In remote agricultural areas, electrical energy is usually deficient for pumping water into greenhouses. Photovoltaic (PV) panels and wind generators are considered suitable options for power supply. The reliability of hybrid generation water pumping depends primarily on the number of system components, which should be adapted to the local climatic conditions and crop irrigation schedule. In this study, a universal size optimization model is established to optimize the configuration of a hybrid PV-wind-battery (PWB) generation system. The climatic conditions and crop irrigation schedule are parameterized in the model. Minimization of the annual cost of the hybrid PWB system is the objective function. The constraints include the battery state of charge (SOC) and the power supply reliability, which consists of the loss of power supply (δLPS) and the excess energy (δEX). The numbers of PV panels and batteries, as well as the rated power of the wind generator, are the decision variables. The optimization model of the PWB generation system is solved using a particle swarm optimization (PSO) algorithm based on penalty function. The model is then applied to determine the optimal configuration of a water pumping system for a greenhouse used to grow tomatoes. Measured climatic data are used in the optimization process, which is conducted in the month of maximum irrigation water requirement (August). The optimal results for this greenhouse are two PV panels and two batteries, and the rated power of the wind generator is 375 W. Furthermore, field experiments are performed to validate the optimization model. The field experiment results show that the total output power of the PV panels and wind generator during 15 d are 41.478 kW and 6.235 kW, respectively. The total load power of the pump is 36.965 kW. The field experiments demonstrate that the optimal results are able to meet the power requirements of the water pumping system and the sizing optimization model is appropriate.

Emitter discharge is one of the most important parameters considered in the design, operation, and management of subsurface irrigation systems. The emitter discharge, if properly chosen, can eliminate surface runoff and minimize deep percolation water losses. The discharge from a ceramic emitter depends on the working pressure head and the ceramic hydraulic conductivity, so it is important to determine the optimal working levels for these two design parameters. In this work, it is confirmed that the HYDRUS-2D predictions of the cumulative infiltration and the horizontal wetting front are in good agreement with experimental results, and that the Hydrus-2D model can be used to accurately simulate soil water movement under subsurface irrigation with ceramic emitters. Additional simulations with HYDRUS-2D were used to study the effects of various design parameters (i.e. working pressure head and ceramic hydraulic conductivity) on emitter discharges in soils, deep percolation and soil wetting fronts. Results show that both the working pressure head and ceramic hydraulic conductivity have significant impact on the discharge of emitters in soil, and the deep percolation water losses. The emitter discharge in soil decreases with time and finally stabilizes. When the working pressure head and ceramic hydraulic conductivity are higher, the stable discharge (emitter discharge in soil at 120 h) is greater, and this situation may increase the risk of deep percolation. The relationship between the working pressure head, ceramic hydraulic conductivity, and stable discharge is developed as a power function. To satisfy the water requirements of trees with an active layer of root systems down to about 0–100 cm in the Loess Plateau in China and reduce the risk of deep percolation, it is recommended that the working pressure head should be 20–50 cm of water and the ceramic hydraulic conductivity should be between 0.1 and 1.9 cm h−1.

Kinetic energy of droplets from big gun sprinklers relates closely to the infiltration process and soil erosion, as well as severely affects the energy consumption of hose-drawn travelers. However, research work related to the kinetic energy distribution of big gun sprinklers is seldom performed. In this study, The radial water application distribution, droplet size distribution, and droplet velocity distribution of a big gun sprinkler were measured. Based on the experimental data, a calculation method was developed to determine the kinetic energy of big gun sprinkler under stationary and moving states. Volume weighted mean particle size and the corresponding equivalent landing velocity were adopted as the feature size and velocity of the point located at any distance from the sprinkler. The droplets’ landing velocities present a logarithmic relationship with droplet size and velocities rise with the increase of droplet size. The operating pressure should not be lower than 0.2 MPa since the peak value of specific power will rise rapidly below this operating pressure. For positions receiving the same kinetic energy, obvious difference may exist in the amount of water and the dynamic process curves of specific power. With the increase in travel speed of the hose-drawn traveler, both the cumulative kinetic energy and the irrigation duration decrease proportionally. Compared to the spray plate sprinklers applied to center pivots, the big gun sprinkler shows a milder precipitation process, but the water application lasts longer and carries more kinetic energy, reaching 2- 4 times for the same amount of water. The infiltration rate of each location decreases linearly along with an increase in distance to the travel lane, and the infiltration rate decreases to approximately 20 mm/h at the end of the spraying area.

In the present study, micro-level analysis of seven months of field irrigation-induced evolution of tensile properties of a disposable drip tape made from a virgin polyethylene mixture and ...

Subsurface irrigation has been achieved by using ceramic emitters, pitchers, pots and ceramic tubes, which have gained a certain degree of interest in arid regions due to their efficient use of water. Research on the formation of wetting patterns around the ceramic emitter is essential for the design of irrigation system. In this study, numerical simulations were carried out to investigate the effects of emitter installation method, emitter buried depth, emitter structural parameters, irrigation doses and initial soil water content on the wetting patterns in clay loam with Hydrus-2D. Finally, two field application experiments were conducted to test the practicality and reliability of simulation results. The simulation results were in good agreement with the experimental data. Results showed, emitter installation method had the least effect on the wetting pattern. A 25 cm buried depth would be suit for irrigating vegetables, a 45 cm deep buried depth would suit for irrigating fruit trees. The structure parameters had a significant effect on cumulative fluxes and horizontal wetting front, the structural parameters (emitter length is 7.00 cm, emitter external diameter is 1.25 cm, and emitter inner diameter is 0.60 cm) would be a better fabricate parameters for ceramic emitter. Wetting front increased with increasing irrigation doses and initial water content. To prevent percolation, when the initial water content was high, it should be better to cut down the irrigation duration of ceramic emitter. The field results indicated that Hydrus-2D could be used to investigate the suitable parameters for ceramic emitter in subsurface irrigation systems and determine the suitable arrangement and operation mode of ceramic emitter.

Emitter clogging has a direct impact on the performance and service life of a drip irrigation system. A study of labyrinth emitter clogging was conducted to determine the effects of pulsating versus constant pressure on average emitter flow rate ( $$\overline{q}$$ ), the Christiansen uniformity coefficient (Cu), and the location of clogged emitters. Under constant pressure, emitters in this study began to be clogged after the 8th irrigation, whereby 15 emitters eventually became clogged; the average emitter flow rate decreased to 75% of the original emitter flow rate ( $${{q}_{0}}$$ ) after the 15th irrigation, and Cu decreased rapidly by 68.2%. For pulsating pressure, emitters began to be clogged after the 14th irrigation, only 5 emitters became clogged, and $$\overline{q}$$ only decreased to 85.3% of $${{q}_{0}}$$ , and Cu declined by only 22.6%. These results demonstrate that the anti-clogging performance of emitters with pulsating pressure is better than with constant pressure. Emitter clogging at a constant pressure generally occurred at the inlet and front of labyrinth channels, mainly due to deposition of sediment particles. Emitter clogging with pulsating pressure is due to other impurities (e.g., debris of Teflon tape) besides sediment particles plugging the labyrinth channel. Pulsating pressure is recommended for use in drip irrigation to prevent emitter clogging.

Uniformity of water distribution plays an important role in evaluating irrigation quality. As necessities in calculating irrigation uniformity during designing a lateral-move sprinkler irrigation system (LMSIS), the water distribution patterns of individual sprinkler in motion are crucial. Considering the limitation of the experiment platform, dynamic water distribution of an isolated sprinkler is difficult to measure, especially for a fixed spray plate sprinkler (FSPS) which LMSIS has been widely equipped with in China, therefore developing a model to simulate dynamic water distribution of a moving sprinkler is necessary. The objective of this study was to develop and validate the theoretical basis for calculating water distribution characteristics of a single FSPS in translational motion applying a superposition method, and provide an optimized operation management of LMSIS. The theoretical model’s validity was verified in an indoor experiment using a Nelson D3000 FSPS in motion with 36 grooves and blue-plate spray heads. The software was programmed using the Eclipse Platform and the software was capable of simulating water distribution pattern and Christiansen uniformity coefficient (Cu). The results indicated that the water distribution simulated by the software presents three peaks of maximum application under varying conditions, and the value of water application peaks decreased as working pressure and/or mounting height increased. Conversely, the wetted diameter increased as working pressure and/or mounting height increased. Working pressure, mounting height, and sprinkler spacing each had a significant effect on the Cu. The Cu increased as working pressure and/or mounting height increased but decreased as sprinkler spacing increased. As a consequence, the model can be used to predict the relative water distribution pattern; and the Cu can be calculated with the simulated data, thus providing a tool for designing a new LMSIS.

Sinusoidal oscillating water flow at low pressure can improve the anti-clogging ability of an emitter in drip irrigation or the water distribution of a nozzle in sprinkler irrigation and reduce the cost and energy consumption of the irrigation system. In this study, the characteristics of instantaneous pressure head attenuation of oscillating water flow along a pipeline have been investigated. By using a complex function to solve the continuity equation and the momentum equation of a pipeline with water hammer motion and using the Darcy&ndash, Weisbach formula to estimate the head loss, a calculation model for the instantaneous pressure head of oscillating water flow along a pipeline was developed. The measured value of the amplitude of the pressure head and the average instantaneous pressure head in the experiments have been used to verify the corresponding pressure head calculated by the model. The results show that the amplitude of the pressure head and the average instantaneous pressure head decrease linearly along the pipeline. The calculated value of the amplitude of the pressure head and the average instantaneous pressure head are basically close to the corresponding measured pressure head. From the results of all the tests, the maximum relative error of the calculated and measured value of the amplitude of the pressure head along the pipeline was 9.44%. The maximum relative error of the calculated and measured value of the average instantaneous pressure head along the pipeline was 8.37%. Hence, the model can accurately predict the instantaneous pressure head of oscillating water flow along a pipe and provide a theoretical basis for the application of oscillating water flow in irrigation systems and the design of irrigation pipe networks.

Laterally-moving sprinkler irrigation systems under low pressure experience problems including small spraying range, low uniformity, surface runoff, and low water utilization rate. To solve these problems, experiments were carried out on a laterally-moving sprinkler irrigation system using a Nelson D3000 sprinkler (Nelson Irrigation Co., Walla Walla, WA, USA) under low pressure, sinusoidal oscillating water flow. The sprinkler intensity and impact kinetic energy intensity distribution were investigated for sprinklers both static and in motion. The test data were used to calculate combined sprinkler intensity and impact kinetic energy intensity uniformity for different nozzle spacings, and were compared with constant water pressure test results. It was found that sinusoidal oscillating water flow can effectively increase spraying range, as well as reducing the peak value of the sprinkler intensity and impact kinetic energy intensity. Within an optimal range of amplitude and nozzle spacing, sinusoidal oscillating water flow significantly improves the combined sprinkler intensity, impact kinetic energy intensity uniformity, and the spraying quality of laterally-moving sprinkler irrigation systems under low pressure conditions. When the average water pressure is 100 kPa, the optimal range of amplitude of sinusoidal oscillating flow applied to the laterally-moving sprinkler irrigation system is 50&ndash, 60 kPa. When the amplitude is 50 kPa, the optimal nozzle spacing is 3.5&ndash, 4 m, when the amplitude is 60 kPa, the optimal nozzle spacing is 3.5&ndash, 4.5 m. The related parameters can provide a reference for the application of sinusoidal oscillating water flow in laterally-moving sprinkler irrigation systems.

Apple trees consume a large amount of water, causing soil desiccation which reduces the land quality in the Loess Plateau. The development of efficient water-saving irrigation technology has become the main way to maintain apple production and prevent land degradation in this area. Subsurface irrigation with ceramic emitters (SICE) is an energy-efficient and water-saving technology for arid and semi-arid regions. However, the effectiveness of SICE for apple trees needs to be researched because of the special environment of the Loess Plateau. In this study, we determined the optimal buried depth of SICE tape, based on the soil water content (SWC), yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) of apple trees over a two-year field experiment. Results shown that SICE buried at a depth of 40 cm significantly improved new shoot length, yield, WUE and IWUE by 15.9%, 7.6%, 14.8% and 6.5% respectively compared to subsurface drip irrigation (SDI). Variations in SWC for SICE buried at a depth of 40 cm were smaller than those for SDI. SICE significantly enhanced yield through its ability to save water and increase soil temperature for apple trees. Our study shows that SICE did not only produce a suitable soil water environment and ensure stable growth of apple trees, but also saved more water resources.

A subsurface irrigation system with ceramic emitters (SICE) without a pump has been developed to limit energy consumption and reduce greenhouse gas emissions. Yet whether SICE can be used in low-pressure conditions has not been tested; moreover, there is no index for evaluating the irrigation quality of SICE. Laboratory experiments, with six treatments, were conducted to study ceramic emitter hydraulic characteristics in the air and soil under different working pressure heads and emitter types. The results indicated that when H increased, the emitter discharge increased linearly, and the discharge deviation decreased in the air. With increased H in the soil, the emitter discharge, soil water content, and soil water content uniformity increased, and the discharge deviation decreased. When H was greater than or equal to 20 cm, the discharge deviation in the soil was less than that in the air, and the soil water content uniformity was higher than 80 %. The soil water content uniformity could be used in the evaluation of the irrigation quality of SICE based on the reliability and convenience of observation. To make the best use of soil water potential on the outflow of the emitter, reduce the discharge deviation, and improve soil water content uniformity, the working pressure head of SICE should be higher than 20 cm.

Labyrinth channels are widely adopted in emitter designs to regulate the water flow. The flow regime and the head loss of labyrinth channels have significant impacts on the hydraulic performance of emitters. In this study, the flow behavior of water passing through an emitter channel is observed using the micro particle image velocimetry (PIV), and the head loss during the flow is analyzed for an emitter with a triangular labyrinth channel. The results show that the flow regime is consistent with the classical theory of hydraulics governing straight channels, even when the cross-sectional area is very small (as small as 0.5 mm×0.5 mm). The critical Reynolds number from laminar to turbulent flows in a labyrinth channel is approximately in a range between 43 and 94. The local head loss factor decreases as the Reynolds number increases for labyrinth channels with smaller cross-sectional areas, such as 0.5 mm×0.5 mm and 1.0 mm×1.0 mm. The local head loss factor is not related to the Reynolds number and is only a function of the boundary conditions of the labyrinth channel when the Reynolds number exceeds approximately 1 000 (for cross-sectional areas of 1.5 mm×1.5 mm and 2.0 mm×2.0 mm). The ratio of the local head loss to the total head loss ( ) first increases and then remains nearly constant as the Reynolds number increases in the labyrinth channel. The head loss in the labyrinth channel is almost equal to the local head loss, ( ) and is approximately 0.95 for cross-sectional areas of greater than 1.0 mm×1.0 mm. These results can be used for optimizing the design of emitter channels.

In this study, a robust finite time Takagi-Sugeno fuzzy control method for hydro-turbine governing system (HTGS) is investigated. Firstly, the mathematical model of HTGS is introduced, and on the basis of Takagi-Sugeno (T-S) fuzzy rules, the T-S fuzzy model of HTGS is presented. Secondly, based on finite time stability theory, a novel finite time Takagi-Sugeno fuzzy control method is designed for the stability control of HTGS. Thirdly, the relatively loose sufficient stability condition is acquired, which could be transformed into a group of linear matrix inequalities (LMIs) via Schur complement as well as the strict mathematical derivation is given. Furthermore, the control method could resist random disturbances, which shows the good robustness. Simulation results indicate the designed finite time T-S fuzzy control scheme works well compared with the conventional method. The approach proposed in this paper is easy to implement and also provides reference for relevant hydropower systems.

This paper studies the application of frequency distributed model for finite-time control of a class of fractional-order nonlinear systems. Firstly, a class of fractional-order nonlinear systems with model uncertainties and external disturbances are introduced, and a new frequency distributed model with theoretical inference is presented. Secondly, a novel fast terminal sliding surface is proposed and its stability to origin is proved based on the frequency distributed model and Lyapunov stability theory. Furthermore, based on finite-time stability and sliding mode control theory, a robust control law to ensure the occurrence of the sliding motion in a finite time is designed for stabilization of the fractional-order nonlinear systems. Finally, two typical examples of three-dimensional nonlinear fractional-order Lorenz system and four-dimensional nonlinear fractional-order Chen system are employed to demonstrate the validity of the proposed method.

A novel fractional order Takagi–Sugeno (T–S) fuzzy control method for a class of fractional order non-linear systems is proposed in this study. On the basis of the fractional order interval theory, the generalised T–S fuzzy model for a class of uncertain fractional order non-linear systems is presented. By using fractional order Lyapunov stability theorem, the more relaxed and practical sufficient stability conditions which are presented as a new set of linear matrix inequalities are put forward, which are guaranteed by rigorous mathematical derivation. The proposed control scheme is developed for fractional order non-linear systems stabilisation in the presence of random disturbances. Typical instances including the fractional order three-dimensional (3D) non-linear system and the fractional order 4D non-linear Lorenz hyperchaos are implemented. Simulation results indicate the designed fractional order T–S fuzzy control scheme works well compared with the existing method.

This study aims to identify the optimal configuration of a hose reel traveling irrigator based on a multi-objective evaluation. We identified nine evaluation indicators (two empirical: irrigation efficiency, yield increase; two technical: spray uniformity, application rate; two economic: initial investment, annual operating costs; three social and environmental: labor intensity, productivity, greenhouse gas emissions) selected from aspects of technology, economy, society and the environment. We evaluated a primary set of seven technical, economic, and social and environmental indicators and a smaller subset of only the technical and economic indicators. The multi-objective evaluation ranked 144 alternatives using Principal component analysis and Data envelopment analysis methods. The optimal scheme was exactly the same for both analysis methods, and the number of schemes within a deviation of five reached 88.2 % of all alternatives. The comparison results support the accuracy of the evaluation and the results were not affected by the evaluation methods. The influence of a single configuration parameter on the comprehensive evaluation efficiency of the hose reel traveling irrigator was discussed. A 200 m pipe length, 0.45 MPa operating pressure of the sprinkler, 0.2R overlapping distance and 65 mm pipe diameter was preferred under the working conditions of the case study. The impacts of social and environmental indicators on the overall evaluation were significant, which can help designers/users make cleaner and more user-friendly configuration schemes of the hose reel traveling irrigator.

Vertical impact and turbine drive sprinklers are the most widely used high-volume sprinklers with both solid set spray and hose-drawn traveler irrigator systems. Different mechanical structures and driving modes between the two types of sprinklers will inevitably lead to differences in spray performance, which may affect the adaptability of each sprinkler. Thus far, there are few comparative studies that have quantitatively analyzed the spray characteristics of the two types of gun sprinklers, resulting in the lack of guidance in sprinkler-type selection for both sprinkler system designers and farmers. In this paper, the vertical impact drive gun sprinkler (50PYC) and turbine drive gun sprinkler (HY50) were used to conduct a comparative analysis of water distribution and kinetic energy distribution between these two commonly-used sprinklers. The results show that the average radial application rate of 50PYC was 11.0%–35.9% higher than that of HY50 under fixed spray conditions. Under mobile spray conditions, the water distribution of the two gun sprinklers initially increased and then decreased as the distance from the travel lane increased, exhibiting a unimodal distribution. Both the cumulative irrigation depth and average radial application rate of 50PYC were significantly higher than those of HY50 in the spray area close to the travel lane. Under overlapping spraying conditions using two adjacent sprinklers of the same type, various working pressures and different spacing between sprinklers, the maximum distribution uniformity coefficients of the 50PYC gun sprinkler reached 80.5% to 87.8%, while the maximum distribution uniformity coefficients of the HY50 gun sprinkler were approximately 67.1% to 76.9% (5.3% to 13.5% lower than that of 50PYC). Under fixed spray conditions, the peak values of spray kinetic energy of the turbine drive-HY50 was about 1.5–2.7 times that of the 50PYC gun sprinkler under different working pressures. Under mobile spray conditions, the cumulative kinetic energy in the whole spray area of the HY50 gun sprinkler was about 1.5–2.4 times that of the 50PYC gun sprinkler. This quantitative study on two common types of sprinkler guns, vertical impact and turbine drive sprinklers, indicates that to comprehensively obtain greater irrigation benefits, soil and crop types, irrigation water quality, and economic and labor costs should also be taken into consideration when selecting between the two gun sprinklers.

Sprinkler irrigation is promoted due to its remarkable advantages in water conservation, but the high energy consumption limits its development in a situation of energy scarcity. In order to determine the energy consumption of a fixed spray-plate sprinkler (FSPS), its discharge and initial trajectory velocity were investigated using a particle image velocimetry (PIV) technique and computational fluid dynamics (CFD) analyses. A nozzle diameter of 4.76 mm was used under windless conditions. Overall, good agreement between simulation results and experimental values was obtained. On the premise that the simulation method produced high accuracy, a series of simulations was performed with different nozzle diameters. The water distribution pattern, stream trajectory velocity and kinetic energy dissipation were analyzed. The results show that the jet produced at the nozzle is split by grooves after it hits the plate, with separation occurring earlier with decreasing nozzle diameter. The area of the flow cross-section of the outlet is mainly influenced by nozzle diameter rather than working pressure. The initial trajectory velocity of the grooves increases logarithmically with increasing working pressure. A high working pressure may not cause large kinetic energy dissipation. The dissipation rate of the FSPS ranged from 28.01&ndash, 50.97%, i.e., a large kinetic energy rate was observed. To reduce this energy dissipation and improve water use efficiency, the structure of the FSPS should be optimized in further research.